Information storage devices are used to retrieve and/or store data in computers and other consumer electronics devices. A magnetic hard disk drive is an example of an information storage device that includes one or more heads that can both read and write, but other information storage devices also include heads—sometimes including heads that cannot write. For convenience, all heads that can read are referred to as “read heads” herein, regardless of other devices and functions the read head may also perform (e.g., writing, flying height control, touch down detection, lapping control, etc).
In a modern magnetic hard disk drive device, each read head is a sub-component of a head gimbal assembly (HGA). The read head typically includes a slider and a read/write transducer. The read/write transducer typically comprises a magneto-resistive read element (e.g., so-called giant magneto-resistive read element, or a tunneling magneto-resistive read element), and an inductive write structure comprising a flat coil deposited by photolithography, and a yoke structure having pole tips that face a disk media. The HGA typically also includes a suspension assembly that includes a mounting plate, a load beam, and a laminated flexure to carry the electrical signals to and from the read head. The read head is typically bonded to a tongue feature of the laminated flexure.
The HGA, in turn, can be a sub-component of a head stack assembly (HSA) that typically includes a plurality of HGAs, a head actuator, and a flex cable. The mounting plate of each suspension assembly can be attached to an arm of the head actuator (e.g. by swaging), and each of the laminated flexures can include a flexure tail that is electrically connected to the HSA's flex cable (e.g., by solder reflow bonding or ultrasonic bonding). The angular position of the HSA, and therefore the position of the read heads relative to data tracks on the disks, can be actively controlled by the head actuator which is typically driven by a voice coil motor (VCM). Specifically, electrical current passed through a coil of the VCM can apply a torque to the head actuator, so that the read head can seek and follow desired data tracks on the spinning disk.
The actuator body of the HSA can be pivotally attached to a base of the disk drive, for example, by a pivot bearing that allows the HSA to pivot. The pivot bearing typically is disposed within a bore formed in the actuator body and bonded thereto by a layer of adhesive. During manufacture a portion of the adhesive that can squeeze out of an adhesive vent in the actuator body into a space located between the actuator body and the flex stiffener. The thin layer of adhesive squeeze out does not get cured during the baking process after pivot adhesive dispensing, which can led to high liquid particle counts within the magnetic disk drive. Such high liquid particle count can thereby contaminate other disk drive components (e.g., the head or disk), reducing the reliability and/or lifetime of the disk drive and threatening the data stored within.